1. Field of the Invention
One embodiment of the present invention relates to a display correction circuit, particularly a display correction circuit including an oxide semiconductor. One embodiment of the present invention relates to a display correction system including the display correction circuit. Note that one embodiment of the present invention is not limited to the technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. One embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specific examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a method for driving any of them, and a method for manufacturing any of them.
2. Description of the Related Art
In recent years, smartphones have been widespread as portable devices. A large display for smartphones is accordingly needed in the market, and a recent mainstream size is 4 inch to 6 inch. Furthermore, many smartphones using an organic EL panel are coming on the market. An organic EL panel has features of flexibility and higher color purity than liquid-crystal panels and is being developed.
Unlike a liquid crystal driven by alternating current, direct voltage or direct current is applied to an organic EL element, a polysilicon transistor, or an oxide semiconductor transistor that are used in an organic EL panel. The organic EL element and transistor to which direct voltage or direct current is applied thus tend to fluctuate in characteristics after driven for a long time. The fluctuation in characteristics of the element appears as display unevenness on the display screen. Generally, a pixel driven for a long time decreases in luminance; thus, only a specific pixel driven for a long time decreases in luminance, which appears as burn-in on the display screen and degrades the display quality. Display unevenness is caused by variation in transistor characteristics as well.
As a measure against it, there is a method in which a correction circuit is incorporated in a pixel of an organic EL panel using a polysilicon transistor or an oxide semiconductor transistor to correct degradation and variation of the element. FIG. 1 shows a specific example of a circuit for correcting threshold of a transistor for driving an organic EL element. A pixel 100 in the circuit includes transistors 101, 102, 103, 104, and 105, a capacitor 106, an organic EL element 108, a data line 109, a power supply line 110, gate lines 111, 112, and 113, an anode line 114, and a cathode 107. Details of the correction circuit are described in Patent Document 1.